Perforated structures

ABSTRACT

A perforated structure, particularly for use as a heat exchanger, comprising two superimposed spaced metal sheet members having tubular projections formed in the respective sheets, the projections of each sheet extending towards the opposite sheet and interfitting with corresponding projections of the opposite sheet, a sealed gallery being formed between the two sheets, of which the following is a specification.

o t Unite States Patent 1151 3,6 Ware n1. M, W72

[54] PERFORATED STRUCTURES 1,286,433 12/1918 Singer ..165/170 1,731,575 10/1929 Hyde .....l65/l30 [72] Invent ware Rugby England 2,856,161 10/1958 Flynn 165/165 x [73] Assignee: Dunlop Holdings Limited, London, En- 3,073,575 1/ 1963 Schulenberg .....165/146 gland 3,308,879 3/1967 Maddocks ..165/167 [22] Ffled: July 1970 Primary Examiner-Kenneth W. Sprague [2i] Appl. No.: 53,098 AttorneyStevens, Davis, Miller & Mlosher 30 Foreign Application Priority Data [571 ABSCT July 11 1969 Great Britain .34 934/69 A Perforated Structure Particularly m use as a heat exchanger, comprising two superimposed spaced metal sheet 521 11.301. ..122/4 R, 165/165, 165/170 members having tubular pmiectiofls fmmqd in reslmfi"e [51 lot. 1C1 ..F22b 13/00 Sheets, the projections of each Sheet extending towards the 1 [58] 11 16111 61 Search ..122/4; 165/130, 131, 146, 165, posite sheet and interfitting with corresponding Projections of 165/166, 167, 168, 169, 170, 171 the opposite sheet, a sealed gallery being formed between the two sheets, of which the following is a specification. [56] References 19 Claims, 9 Drawing ni nm UNITED STATES PATENTS 1,844,452 2/1932 Watson ..165/130 Patented March 14, 1972 3,648,665

4 Sheets-Sheet 1 kl I OOO

14 QQQ 4 10 ---;JTF-3 Patented March 14, 1972 I I 3,648,665

4 Sheets-Sheet 2 I l I), A

Patented March 14, 1972 4 Sheets-Sheet 5 FIG. 7

Patented Mall-ch 14, 1-972 4 Sheets-Sheet 4 PERFORATEID STRUCTURES This invention relates to perforated structures, and particularly to heat exchangers.

One object of the present invention is to provide an improved heat exchanger.

According to one aspect of the invention a perforated structure comprises a first metal sheet member and a second metal sheet member arranged in spaced superimposed relationship to one another and sealed around their edges to form a gallery between the sheet members, the sheet member assembly having a plurality of apertures arranged in pairs, each pair comprising one aperture in each sheet and the apertures of each pair being superimposed, the sheet metal surrounding each aperture of each pair of apertures extending as a tubular projection towards the opposite sheet member into interfitting association with the tubular projection formed from the sheet metal surrounding the other aperture of the pair.

According to another aspect of the invention a heat exchanger element comprises a first metal sheet member and a second metal sheet member arranged in spaced superimposed relationship to one another and sealed around their edges to form a gallery between the sheet members, the sheet member assembly having a plurality of apertures arranged in pairs, each pair comprising one aperture in each sheet member and the apertures of each pair being superimposed, the sheet metal surrounding each aperture of each pair of apertures extending as a tubular projection towards the opposite sheet member into interfitting sealing association with the tubular projection formed from the sheet metal surrounding the other aperture of the pair.

According to a further aspect of the invention a boiler comprises a heat exchanger element as defined above in conjunction with a burner element.

Various embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic plan view of a heat exchanger element;

FIG. 2 is a diagrammatic elevation, partly in section, of the element shown in FIG. 1;

FIG. 3 is a diagrammatic enlarged detail plan view to illustrate the fluid flow in the element illustrated in FIGS. 1 and 2;

FIG. 4 is a diagrammatic enlarged detail sectional view of part of the element illustrated in FIGS. 1 and 2',

FIG. 5 is a diagrammatic detail plan view showing an alternative heat exchanger element;

FIG. 6 is a diagrammatic sectional elevation of an assembly of elements of the kind illustrated in FIG. 5;

FIG. 7 is a diagrammatic perspective view showing a boiler assembly, parts being broken away for clarity;

FIG. 8 is a diagrammatic sectional elevation of the boiler assembly shown in FIG. 7;

FIG. 9 is a diagrammatic, partly broken away perspective view showing an alternative boiler assembly.

The heat exchanger element 1 shown in FIGS. 1 and 2 comprises a first sheet metal member 2 and a second sheet metal member 3 arranged in spaced superimposed relationship. The members 2 and 3 are sealed around their edges by a joint 4 in which the edge of the member 2 is folded around the edge of the member 3 and soldered thereto. Thus a gallery 5 is formed between the sheet members and communicates, through inlet and outlet zones 6 and 7 respectively with a fluid inlet pipe 8 and a fluid outlet pipe 9. The inlet and outlet zones 6 and 7 are formed as trough-shaped depressions in the sheet member 2.

The sheet members 2 and 3 each comprise a plurality of apertures 10 arranged in a regular pattern of rows 11-17 extending transversely relative to the direction of flow of fluid through the gallery the apertures 10 of each row being staggered relative to the apertures of the next adjacent row or rows (see FIG. 3). The apertures 10 of the respective sheet members are arranged in superimposed pairs, each pair comprising one aperture in each sheet. The sheet metal surrounding each aperture 10 in the sheet member 2 extends as a tubular projection 18 towards the opposite sheet member 3 into interfltting engagement with a corresponding tubular projection 19 formed from the sheet metal surrounding the other aperture of the pair, in the sheet member 3, to form a tube 13,19.

The tubular projections 18 and 19 are formed in each respective sheet member by a pressing operation between a plate carrying circular punches arranged in the pattern illustrated and a correspondingly aperturedl die plate. The projections are formed by the punches and their ends are pierced in this operation to form the apertures 10. The projections 13,19 are formed with cylindrical outer ends, the diameters of which are arranged so that the sheet members can be joined together as illustrated, with the projections 13 and 19 interfitting (see FIG. 4). In the assembly operation the projections 13 and 19 are sealed together by well-known soldering or brazing techniques to provide apertures 10 passing through the assembly and sealed from the gallery 5.

In order to improve the rigidity of the assembly and to space the sheet members apart accurately at a predetermined distance so as to ensure a predetermined spacing between the walls of the gallery, the sheet members 2 and 3 are formed with mutually engaging dimpled shoul-der areas 20,21 which may be soldered, welded or riveted together. Securing means of this kind may optionally be provided in spaced positions within the area of the element as well as: at the edges.

In operation the heat exchanger element 1 may be incorporated in a boiler comprising a burner from which hot gases are arranged to pass through the apertures 10 as indicated by the arrows in FIG. 2. Water is circulated through the element from the inlet pipe 8 to the outlet pipe 9, and in passing through the gallery 5 it is caused to flow in a turbulent manner around the tubes 18,19 surrounding the apertures 10 (see FIG. 3). This turbulent flow improves the transfer of heat to the water, and the large number of air passages constituted by the apertures 10 also provides the element with good heat transfer properties at high flow rates.

It will be noted that owing to the staggering of the apertures 10 in the successive rows Ill-17 the flow of liquid through the element is rendered more turbulent when passing through the element in the direction between the positions of the inlet and outlet as shown than would be the case if the liquid was arranged to flow parallel to the rows 11-17. In the arrangement shown each tube 18,19 divides the flow of liquid emerging from the gap between the tubes in the next row on the up stream side.

An important advantage of the heat exchanger element described above is that it is characterized by great simplicity in construction, the gas flow passages 10 being formed entirely from the material of the two sheet members by a simple punching operation.

Two or more elements as described above may be arranged in series, e.g., in a stack of horizontally disposed elements to extract heat from a common source of hot gases.

FIGS. 5 and 6 illustrate an arrangement in which transfer of heat between one fluid and two other fluids may be achieved. In this arrangement an element 30 of the kind described above with reference to FIGS. 1-4 is provided with further finned tubes 31 passing through apertures 32 formed through the element (corresponding to the apertures 10 of FIGS. 1-4). The tubes 31, which each comprise four longitudinally extending fins 33 may pass through more than one element 30 as indicated in dotted lines in FIG. 6.

In operation, air may be passed through the apertures 32 as indicated, in the spaces between the fins 33, and/or transversely to the tubes in the spaces between successive elements 311. Thus separate fluids circulating both in the tubes 31 and in the gallery of the element 30 may be heated or cooled simultaneously.

FIGS. 7 and 8 illustrate the application of heat exchanger elements, generally of the kind shown in FIGS. 1-4, to a boiler assembly 40 incorporating gas burner elements which are of a kind having a similar general form to the heat exchanger ele ments described with reference to FIGS. 1-4 but having unsealed, grooved, interfltting tubular projections to enable gas supplied to the gallery to escape into a combustion zone where it burns with combustion air fed through the apertures. Burner elements of this kind, referred to herein as burner elements of the kind described" are disclosed in the specification of U.S. Patent application Ser. No. 34,934/69.

The boiler assembly 40 comprises a casing 41 having a flue 42 (not shown in FIG. 7) and an air blower 43 to assist the generally upward movement of combustion air through the assembly. Four burner elements 44 of the kind described are arranged in two pairs each of inverted V-shape, and eight heat exchanger elements 45 are located in four pairs of spaced elements arranged flanking and parallel to the respective burner elements, tiltedtowards one another over the burner elements in inverted V-formation so as to receive the hot gases generated by the burners. A gas supply manifold 46 is provided for the elements 44 and water pipe connections 47 are provided for the circulation of water through the heat exchanger elements 45 the elements 45 of each pair being in series. The flow of combustion gases through the elements 45 is illustrated diagrammatically by the arrows in FIG. 8.

The heat exchanger elements 45 embody apertures 48 formed by interengaging tubular projections as in the embodiment illustrated in FIGS. 1-4, but the fluid inlet and outlet Zones, which are only illustrated diagrammatically in FIG. 7, may take any convenient form.

FIG. 9 shows an alternative boiler assembly 60 incorporating an air supply from a balanced flue 61. The boiler casing 62 encloses an outer flue outlet passage 63 and combustion air is drawn through an inlet passage 64 by a blower 65 which passes the air downwardly into a burner and heat exchanger assembly incorporating three vertically mounted burner elements 66 mounted edge-to-edge in triangular plan form on a closed base. Two heat exchanger elements 67 are provided adjacent each burner element 66 to receive the hot combustion gases as indicated by the arrows, and these burner and heat exchanger elements are of the general kind described above with reference to FIGS. 7 and 8. The elements of each pair of heat exchanger elements 67 are arranged in series, being supplied with water through inlet pipes 68 and having outlets 69.

The examples described above relate to heat exchanger elements, but perforated structures in accordance with the invention are also applicable to gas distribution systems or evaporators in which the gas or liquid to be distributed is fed to the gallery and is arranged to be allowed to escape, for example by grooving, or otherwise not sealing, the tubular projections together. The gas or liquid is then arranged to be carried away from the perforated structure by a forced draught of air flowing through the perforations.

A combined evaporator and distributor of this kind may be used for dispersing liquid nitrogen to provide a stream of cold gas for use in quickfreezing of food. Another example of the use of a device of this kind is in the evaporation of water, the device acting as a temperature-reducing and humidifying element in an air-conditioning system.

Having now described my invention what I claim is l. A heat exchanger element comprising a first metal sheet member and a second metal sheet member arranged in spaced superimposed relationship to one another and sealed around their edges to form a gallery between the sheet members, the sheet member assembly having a plurality of apertures arranged in pairs and the plurality of apertures in each sheet are arranged in parallel rows, each pair comprising one aperture in each sheet and the apertures of each pair being superimposed, the sheet metal surrounding each aperture of each pair of apertures extending as a tubular projection towards the opposite sheet member into interfitting association with the tubular projection formed from the sheet metal surrounding the other aperture of the pair, the apertures forming a plurality of tubular passages extending in a direction substantially at right angles to the plane of the sheet member assembly.

2. A heat exchanger element according to claim 1, wherein an inlet zone and an outlet zone are formed in the sheet member assembly for the flow of a fluid through said gallery.

3. A heat exchanger element according to claim 1, wherein said tubular passages are arranged in parallel rows, the tubular passages in one row staggered relative to the tubular passages of the next adjacent row so that a plane intersecting the parallel planes of the axes of said passages located in said parallel rows cannot intersect said planes in a substantially normal direction and contain the axes of two passages which are located in two adjacent rows.

4. A heat exchanger element according to claim 1, wherein said tubular passages have a substantially circular cross-sec tional configuration.

5. A heat exchanger element assembly comprising a heat exchanger element according to claim 1, and a plurality of tubes, each tube extending through a tubular passage of said element.

6. A heat exchanger element assembly according to claim 5, wherein fins are provided on each of said tubes.

7. A heat exchanger element assembly comprising a plurality of heat exchanger elements according to claim 1 and a plurality of tubes extending through the tubular passages in each of the plurality of heat exchanger elements.

8. A boiler assembly incorporating a heat exchanger element according to claim 1, a source of hot gas, and ducting to direct a flow of hot gas from the source of hot gas through the tubular passages of said heat exchanger element.

9. A boiler assembly according to claim 8, wherein a burner element comprises a source of hot gas.

10. A boiler assembly according to claim 8, wherein a plurality of said heat exchanger elements and the source of hot gas are contained in a casing, the heat exchanger elements being arranged in an inverted V-configuration over the source of hot gas.

11. A boiler assembly according to claim 10, wherein at least two of said heat exchanger elements are provided on each side of the source of hot gas.

12. A boiler assembly according to claim 11, wherein a common casing contains two pairs of said heat exchanger elements and two of said sources of hot gas.

13. A boiler assembly according to claim 10, wherein an air blower is provided within the assembly to assist the generally upward movement of combustion air through said source of hot gas. 7

14. A boiler assembly according to claim 10, wherein said burner element, said heat exchanger element, and an air blower are contained within a casing, the burner element and the heat exchanger element arranged in side by side relationship and the air blower arranged to force a flow of combustion air downwardly through the burner element and the heat exchanger element.

15. A boiler assembly according to claim 14, comprising three of said heat exchanger elements, and three of said burner elements vertically mounted in an edge-to-edge triangular plan form.

16. A boiler assembly according to claim 14, wherein two of said heat exchanger elements are associated with each of said burner elements.

17. A heat exchanger element according to claim 2 wherein at least one of the inlet and outlet zones is formed as a troughshaped depression in one sheet member.

18. A heat exchanger element according to claim 1 wherein at least one sheet member is provided with a shoulder area to engage the other sheet member so as to provide a predetermined spacing between the walls of the gallery.

19. A heat exchanger element according to claim 18 wherein the sheet members are secured together in the shoulder area. 

1. A heat exchanger element comprising a first metal sheet member and a second metal sheet member arranged in spaced superimposed relationship to one another and sealed around their edges to form a gallery between the sheet members, the sheet member assembly having a plurality of apertures arranged in pairs and the plurality of apertures in each sheet are arranged in parallel rows, each pair comprising one aperture in each sheet and the apertures of each pair being superimposed, the sheet metal surrounding each aperture of each pair of apertures extending as a tubular projection towards the opposite sheet member into interfitting association with the tubular projection formed from the sheet metal surrounding the other aperture of the pair, the apertures forming a plurality of tubular passages extending in a direction substantially at right angles to the plane of the sheet member assembly.
 2. A heat exchanger element according to claim 1, wherein an inlet zone and an outlet zone are formed in the sheet member assembly for the flow of a fluid through said gallery.
 3. A heat exchanger element according to claim 1, wherein said tubular passages are arranged in parallel rows, the tubular passages in one row staggered relative to the tubular passages of the next adjacent row so that a plane intersecting the parallel planes of the axes of said passages located in said parallel rows cannot intersect said planes in a substantially normal direction and contain the axes of two passages which are located in two adjacent rows.
 4. A heat exchanger element according to claim 1, wherein said tubular passages have a substantially circular cross-sectional configuration.
 5. A heat exchanger element assembly comprising a heat exchanger element according to claim 1, and a plurality of tubes, each tube extending through a tubular passage of said element.
 6. A heat exchanger element assembly according to claim 5, wherein fins are provided on each of said tubes.
 7. A heat exchanger element assembly comprising a plurality of heat exchanger elements according to claim 1 and a plurality of tubes extending through the tubular passages in each of the plurality of heat exchanger elements.
 8. A boiler assembly incorporating a heat exchanger element according to claim 1, a source of hot gas, and ducting to direct a flow of hot gas from the source of hot gas through the tubular passages of said heat exchanger element.
 9. A boiler assembly according to claim 8, wherein a burner element comprises a source of hot gas.
 10. A boiler assembly according to claim 8, wherein a plurality of said heat exchanger elements and the source of hot gas are contained in a casing, the heat exchanger elements being arranged in an inverted V-configuration over the source of hot gas.
 11. A boiler assembly according to claim 10, wherein at least two of said heat exchanger elements are provided on each side of the source of hot gas.
 12. A boiler assembly according to claim 11, wherein a common casing contains two pairs of said heat exchanger elements and two of said sources of hot gas.
 13. A boiler assembly according to claim 10, wherein an air blower is provided within the assembly to assist the generally upward movement of combustion air through said source of hot gas.
 14. A boiler assembly according to claim 10, wherein said burner element, said heat exchanger element, and an air blower are contained within a casing, the burner element and the heat exchaNger element arranged in side by side relationship and the air blower arranged to force a flow of combustion air downwardly through the burner element and the heat exchanger element.
 15. A boiler assembly according to claim 14, comprising three of said heat exchanger elements, and three of said burner elements vertically mounted in an edge-to-edge triangular plan form.
 16. A boiler assembly according to claim 14, wherein two of said heat exchanger elements are associated with each of said burner elements.
 17. A heat exchanger element according to claim 2 wherein at least one of the inlet and outlet zones is formed as a trough-shaped depression in one sheet member.
 18. A heat exchanger element according to claim 1 wherein at least one sheet member is provided with a shoulder area to engage the other sheet member so as to provide a predetermined spacing between the walls of the gallery.
 19. A heat exchanger element according to claim 18 wherein the sheet members are secured together in the shoulder area. 